Apparatus and method for correcting error in a multiple-input multiple-output communication system

Abstract

A method for performing Forward Error Correction (FEC) in a Turbo-Bell Labs Layered Space-Time (BLAST) Multiple-Input Multiple-Output (MIMO) communication system. The FEC method includes performing soft decision on a frame received via a plurality of antennas; performing iterative decoding on the soft decision result value a predetermined number of times, and outputting Log Likelihood Ratio (LLR) values for information bits and first parity bits constituting the frame; generating second parity bits by coding information bits calculated from the LLR values, and comparing the first parity bits calculated from the LLR values with the coded second parity bits; and if the first parity bits are identical to the second parity bits, outputting the information bits, determining that there is no error, and if the first parity bits are not identical to the second parity bits, feeding back the LLR values as a-priori information of the soft decision, and returning to the performing of soft decision.

Description

PRIORITY [0001] This application claims priority under 35 U.S.C. § 119(a) to a Korean Patent Application filed in the Korean Intellectual Property Office on Jul. 27, 2006 and assigned Serial No. 2006-70852, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates generally to an apparatus and method for correcting errors in a Multiple-Input Multiple-Output (MIMO) communication system, and in particular, to an apparatus and method for performing Forward Error Correction (FEC) using a turbo code. [0004] 2. Description of the Related Art [0005] A MIMO communication system, in which a transmitter and a receiver each use multiple antennas, can increase channel transmission capacity in proportion to the number of antennas without additional allocation of frequency or transmission power, compared to the single-antenna system. [0006] The most general reception method of the MIMO system incl...

AI Technical Summary

Benefits of technology

[0052] An aspect of the present invention is to address at least the problems above and / or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an error correction apparatus and method for efficiently stopping iterative decoding in a MIMO communication system.

[0053] Another aspect of the present invention is to provide an error correction apparatus and method for efficiently stopping iterative decoding without greatly increasing complexity and frequency band of a receiver in a communication system that cannot use a CRC technique.

Problems solved by technology

Actually, however, because errors may inevitably occur, the system should use the BLAST technique, a Coding technique, and an Iteration technique of the two techniques to approach the theoretical maximum capacity, i.e. the Shannon capacity.

An increase in the iteration of the MIMO detector and channel decoder operations contributes to an increase of the system performance, but causes an increase in the hardware complexity and time delay.

Because this decoding stopping scheme is available only with experimental simulation, its actual realization is impossible.

However, the CRC stopping criterion scheme suffers from overhead caused by a CRC bit at every frame, and when there is no CRC bit in a frame input by means of frame division in a decoding process, it is not possible to decode the corresponding frame using the CRC stopping criterion scheme.

However, the Approximated Cross Entropy Stopping Criterion scheme should perform an exp(*) operation separately for each SISO decoder to set a criterion in each iterative decoding process, and the hardware complexity increases due to the exp(*) operation.

However, because the Minimum Absolute LLR Stopping Criterion scheme stops iterative decoding only with the information detected by the current SISO decoder other than the two SISO decoders, it may suffer from performance degradation in terms of a Frame Error Rate (FER).

In this case where the thresholds are adaptively applied, the scheme can prevent the FER performance degradation, but may suffer from an increase in the average number of iterations.

If the value p used as a threshold is increased to solve the problem that the Sign Difference Ratio Stopping Criterion scheme is greater than the Hard Decision-Aided Stopping Criterion scheme in the average number of iterations, the Sign Difference Ratio Stopping Criterion scheme can reduce the average number of iterations, but may suffer from FER performance degradation.

As described above, most conventional stopping techniques are low in reliability, so the highest-reliability CRC technique for iterative decoding stopping is generally used.

Therefore, the WiBro system cannot use the CRC technique for each coding block.

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